An agency I signed up with got me a temp job doing data entry. It was supposed to start last week, but the start date has been postponed - three times. It's irritating, since I'm suspending my job search in the meantime (don't want to get a call for an interview while I'm working!), but I've committed to the position.
Don't stop your job search until you actually get $$$ in your pocket from the job you've "committed" to. One day out of the blue, a recruiter called me and said that a three-week contract position had opened up, which would probably turn into a permanent position if I played my cards right, and that I should get down there and do a trial run with them for a day. After a few hours, they came down to the job site and I signed the contract. All was well -- or so I thought. By end of day, my team leader called me aside and said that, "you know, it's just not working out" and that they wouldn't be needing my services after all. Meanwhile, they'd emailed my recruiter and told them that the project had been truncated from three weeks to two days, and that since they were running late, I'd been let go. (Yeah,
riiiight.) Now, if I had been foolish, I would have called off all my job searches because after all, I had a job already, right? -- good thing I didn't. As a matter of fact, as I was walking into the contract site, another recruiter called me up, and I told her that I would get back to her the next day. And I did.
Moral of the story: even when you DO have a job, you might not have one by the end of the day -- so always keep your options open, and keep right on looking.